The present invention relates to a printing apparatus and a multiple type printing apparatus capable of printing on a plurality of pieces of paper. More specifically, the present invention relates to a technique effective when applied to, for example, a thermal printing apparatus provided with a thermal head (what is known as a thermal printer).
Printers used as information output apparatuses are broken down into impact printers, such as wire dot printers, and non-impact printers. Non-impact printers include laser printers and thermal printers. Since impact printers make a high amount of noise and are inferior in print quality, non-impact printers have been more popularly used recently. Among non-impact printers, thermal printers are suited for miniaturization, and thus, they have been used in a wide range of fields.
In particular, in the field of POS (point-of-sales) terminals, since output paper for a receipt to be handed to a customer and output paper for a journal to be kept as a copy for the shop have to be printed simultaneously, two printers are provided in parallel with each other or a dual type printer that has two heads has been put to practical use. However, since a printhead for a printer is expensive, with a multiple, type printer having heads for the respective paper, though it can be made compact to some extent, satisfactory effects with regard to cost can not be obtained.
Accordingly, an invention has been proposed with regard to a dual type thermal printer. which, by sharing a thermal head and providing two paper feed units in parallel with each other with respect to the shared thermal head, attains improvement with regard to both miniaturization and economical efficiency (Japanese Patent No. 2819595).
However, though the thermal printer according to the invention described in Japanese Patent No. 2819595 has an advantage that it is a low-priced apparatus capable of printing on two pieces of paper simultaneously, since it has only one drive roller and one motor, and the guide portion of its paper feed mechanism is fixed, the width of paper to be printed is fixed and the print speed has to be the same with regard to the two systems, and thus, it is found that there is a problem that the printer is difficult to use for general purposes.
Especially with regard to POS terminals, there are many cases where the outputted information and the amount thereof are required to be different between output paper for a receipt to be handed to a customer and output paper for a journal to be kept as a copy for the shop. Accordingly, when the thermal printer according to the patented prior invention mentioned in the above is used for a POS terminal, two kinds of such printers must be prepared for two kinds of paper different in size ratio, preventing drastic decrease in the cost.
In addition, since the thermal printer according to the invention described in Japanese Patent No. 2819595 has only one drive roller and one motor, the print speed for the two kinds of paper can not be made different. Therefore, it is found that, in case the difference in the amount of the outputted information is large, i.e., the amount of the information is extremely different, there is a problem that paper having smaller amounts of information wastes large blank portions of the paper.